GCSE / O Levels Chemistry

Carbonates react with dilute acids to produce carbon dioxide. A student uses excess carbonate
and 100 cm³ of 0.1 mol/dm³ acid and measures the volume of gas produced at regular time
intervals.
The results give line X on the graph. The student repeats the experiment using 50 cm³ of
0.2 mol/dm³ acid whilst keeping everything else the same.
Which line shows the results for the second experiment?
volume of
gas/cm³
0
B
time/s
A
·X
D

Choice B is correct because:

The second experiment which uses 50 cm3 of 0.2 mol/dm3 acid is more concentrated than the first experiment shown by line X on the graph.

Therefore, the second reaction will have a steeper slope than line X as it has a greater rate of reaction.

Next, compare the number of moles in both experiments:

For experiment 1: moles: 0.1 x (100/1000) = 0.01 mol

For experiment 2: moles: 0.2 x (50/1000) = 0.01 mol

Since the number of moles in both the experiments are the same, hence the volume of gas produced for experiment 1 and 2 will be equal.

Therefore, line B accurately shows the results for the second experiment.

Choices A, C and D are incorrect because their lines do not accurately show the results for the second experiment.

Rate of Reaction | 2022 - O/N - 5070/12 | Q22